n-Hexadecane was studied for oral toxicity in single dose toxicity test at 500, 1000 and 2000 mg/kg, and in a 28-day repeat dose toxicity test at doses of 0, 8, 40, 200 and 1000 mg/kg/day. n-Hexadecane was also tested for mutagenicity with assays for reverse mutation in bacteria and chromosomal aberrations in cultured Chinese hamster (CHL) cells.

The single dose oral toxicity test revealed LD50s of above 2000 mg/kg in both sexes.

In the repeat dose study, hematological analyses showed a prolongation of prothrombin time in males of the 1000 mg/kg group, and a decrease in erythrocyte counts in females of the 200 and 1000 mg/kg groups. A significant increase in GPT was detected in males and females of the 1000 mg/kg group. These changes disappeared after a recovery period. NOELs for repeat dose toxicity were 200 mg/kg/day in males and 40 mg/kg/day in females.

n-Hexadecane was not mutagenic for S.typhimurium TA100, TA1535, TA98, TA1537, and E. coli WP2 uvrA with or without exogenous metabolic activation up to 5000 μg/plate. In addition, this chemical induced neither chromosomal aberrations nor polyploidy with or without an exogenous metabolic activation system up to 1 mg/ml.

n-Hexadecane[544-76-3]

1. Single Dose Oral Toxicity 1)

Purity	:	99.8 %
Test species/strain	:	Rat/Crj:CD (SD)
Test method	:	OECD Test Guideline 401
Doses	:	500, 1000, 2000 mg/kg
Number of animals	:	Male, 5; Female, 5/group
GLP	:	Yes
Test results	:	LD50: Male > 2000 mg/kg, Female > 2000 mg/kg

2. Repeat Dose Toxicity 1)

Purity	:	99.9 %
Test species/strain	:	Rat/Crj:CD (SD)
Test method	:	Guidelines 28-Day Repeat Dose Toxicity Test of Chemicals (Japan)
Route	:	Oral (gavage)
Doses	:	0 (vehicle), 8, 40, 200, 1000mg/kg/day
Number of animals	:	Male, 10 or 15 (0, 1000 mg/kg); Female, 10 or 15 ( 0, 1000 mg/kg)
Vehicle	:	Corn oil
Administration period	:	Male, Female; 28 days
Terminal kill	:	Male, Female; days 29 or 43
GLP	:	Yes

　Test results:

No abnormal clinical signs or deaths were seen. Body weight gains for all doses in both sexes were almost the same as those of the controls. n-Hexadecane did not cause any changes in food consumption, water intake or urinalysis parameters.

On hematological analyses, the 1000 mg/kg males showed significantly prolonged prothrombin time, 200 mg/kg and 1000 mg/kg females exhibited significant decrease in erythrocyte counts, and 1000 mg/kg females showed increased mean corpuscular hemoglobin. These changes disappeared after the recovery period. On blood biochemical analysis, a significant increase in GPT was detected in the1000 mg/kg males and females, but a return to normal value was evident after the recovery period.

No significant differences were noted in organ weights and pathological findings between any dose groups.

NOEL: Male 200 mg/kg/day, Female 40 mg/kg/day,

3. Genetic Toxicity

3-1 Bacterial test 2)

Purity	:	99.8%
Test species/strains	:	S. typhimurium TA100, TA1535, TA98, TA1537 E. coli WP2 uvrA
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Procedure	:	Plate method
Solvent	:	Acetone
Positive controls	:	-S9, AF-2 (TA100,WP2 uvrA,TA98), sodium azide (TA1535) and 9-aminoacridine (TA1537) +S9, 2-Aminoanthracene (all strains)
Doses	:	0, 312.5, 625, 1250, 2500, 5000 μg/plate
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	3
Number of replicates	:	2
GLP	:	Yes

　Test results:

Minimum concentration of test substance at which toxicity to bacteria was observed:
No toxicity was observed up to a concentration of 5000 μg/plate with or without metabolic activation.

Genotoxic effects:
S. typhimurium TA100, TA1535, TA98, TA1537

	+	?	-
with metabolic activation:	[ ]	[ ]	[*]
without metabolic activation:	[ ]	[ ]	[*]

E. coli WP2 uvrA

	+	?	-
with metabolic activation:	[ ]	[ ]	[*]
without metabolic activation:	[ ]	[ ]	[*]

3-2 Non-bacterial in vitro test (Chromosomal aberration) 2)

Purity	:	99.8 %
Type of cell used	:	Chinese hamster CHL cells
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Solvent	:	Acetone
Positive controls	:	-S9, Mitomycin C +S9, Cyclophosphamide
Doses	:	-S9: 0, 0.25, 0.5, 1mg/ml +S9: 0, 0.25, 0.5, 1 mg/ml
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	2
GLP	:	Yes

　Test results:

n-Hexadecane induced neither chromosomal aberrations nor polyploidy up to the concentration of 1 mg/ml with or without an exogenous metabolic activation system.

Lowest concentration producing cytogenetic toxicity:

with metabolic activation: > 1 mg/ml

without metabolic activation: > 1 mg/ml

Genotoxic effects:

	+	?	-
with metabolic activation:	[ ]	[ ]	[*]
without metabolic activation:	[ ]	[ ]	[*]

1)	The tests were performed by Nihon Bioresearch Inc., Hashima Laboratory, 6-104 Majima, Fukuju-cho, Hashima, Gifu, 501-62, Japan. Tel 81-583-92-6222 Fax 81-583-92-1284
2)	The tests were performed by the Hatano Research Institute, Food and Drug Safety Center, 729-5 Ochiai, Hadano-shi, Kanagawa, 257, Japan. Tel 81-463-82-4751 Fax 81-463-82-9627